An increasing problem of airborne microorganisms, including viruses (e.g. influenza and SARS), as well as of microbial and other antigens and toxins, resulting in increased morbidity and mortality due to aggressive viruses, resistant bacteria and sensitivity to allergens and toxins, requires an efficient method to remove these agents and molecules from contaminated air of various environments and premises. The latter include environments with conventional air filters, such as hospital operating theatres and hospital ward rooms, e.g. ward rooms for severely immuno suppressed patients. In modern hospitals, an increasing number of patients are receiving immunosuppressive therapy for cancer and other serious diseases making them highly sensitive to a variety of infectious agents, while patients who have been struck by highly contagious agents are treated in infectious disease isolation wards that are commonly situated within the same hospital buildings. Also, other environments where presently no air filters are in common use, including day care centres, kindergartens and schools, especially for small children, air-borne microorganisms (e.g. penicillin-resistant pneumococci causing middle ear inflammation and pneumonia) may pose a threat, and such environments would thus benefit from air-cleaning measures. Furthermore, premises used in the globally fast growing poultry industry and other food production require efficient removal of viruses and bacteria from air to reduce the risk of microbial contamination and exchange of organisms that may undergo genetic recombination potentially resulting in epidemic outbreaks of serious infections, such as the bird and swine flu. Also, in transportation vehicles, including airplanes, conventional air conditioning equipment may carry microorganisms from one infected passenger to other passengers.
Conventional mesh network air filters have limited capacity to capture small bacteria, viruses and components of microorganisms, as well as molecules like allergens and toxins. The most advanced conventional filter system is the High Efficiency Particulate Air (HEPA) filter which is preferably used for cleaning the air in high risk laboratories. One disadvantage with mesh network filters is their inherent inability to kill infectious agents that may have been caught by the filter. Another disadvantage is that they get clogged and become inefficient after variable periods of time and then can potentially start leaking because of the high air pressure that is then required to overcome the filter resistance. Notably, bound infectious microorganisms may then detach and pose a risk to individuals in the environment.
Today there are patents or patent applications on conventional filters based on mesh networks with the capacity to clean the air from microorganisms, including patent applications based on capturing microorganisms by electrostatic binding. The above mentioned drawback with mesh network filters, including HEPA-filters, with their gradual clogging leads to increasing air resistance and decreasing filtering efficiency over time. These insufficiencies, which are difficult to detect and control, pose a risk despite the fact HEPA-filters are usually regularly exchanged over time. Moreover, the exchange procedure of mesh network filters, including HEPA-filters, is in itself connected with a certain risk of spreading infectious microorganisms stuck in the filter. Finally, HEPA filters are generally expensive and require efficient pre-filtering systems.
Because of the increasing air traffic between countries and continents this mode of transmission of microorganisms will have to be taken seriously. Finally, the global climate changes that are thought to take place will most likely affect the disease panorama in many parts of the world and, among other things, result in increased demand for efficient removal of viruses and other microorganisms, as well as allergens and toxins, from air.
Accordingly there is an increasing need for a new technique for taking care of the problems with airborne harmful agents.